It is conventional in the food service industry to serve or display food from a box-like refrigeration unit having one or more openings adapted to receive pans of food. Such units typically have a work surface which is relatively planar and horizontal, and disposed at about waist height, and a storage compartment below. In many instances the work surface has a single, elongated opening, allowing several pans to be stacked in a row, side by side, within the opening. A unitary and rectangular opening is generally employed when rectangular and box-like pans are used, and alternatively, a series of circular openings arranged side by side is generally employed when cylindrical or bowl-like pans are used. The pans are usually removable for refilling, cleaning and the like, and are generally suspended by an upper lip from the work surface so that the top of each the pan is nearly flush with the work surface. Such refrigeration units are often employed as part of a salad bar or food preparation station.
The main difficulty with refrigeration units of the type just described is the difficulty of cost-effectively maintaining the proper temperature of food contained within the various exposed pans. To some extent this difficulty is a function of the close stacking of pans, which impedes cooling of the pans. This in turn allows food within the pans to warm up, especially food near the top and central portions of the pans. Warmed food is undesirable for many reasons, including an increased danger that the warmer temperatures will lead to the growth of bacteria within the food. The situation is exacerbated by high ambient temperatures, such as may be present in a hot kitchen environment, and by the practice of leaving food in cooling pans for substantial period of time. Prep tables, for example, which are one category of refrigerated food service and display unit, are typically located next to ovens and ranges which may expose food to temperatures in excess of+75.degree. F. The location of prep tables next to such heat sources has historically allowed food to reach undesirable temperatures such as+55.degree. F. and above.
One of the most common methods of cooling foods contained in refrigerated food service and display units is packing the pans in ice. While useful in many instances, ice is often unsatisfactory because it is not cold enough to keep foods deep within the pans at proper temperature. It is also known to circulate cooled water or other liquid about the pans, but that solution is problematic since the pans tend to float on the circulating liquid, and the circulating liquid may tend to accumulate microorganisms and debris.
Another common method of cooling foods contained in refrigerated food service and display units is to cool the entire inside space of the storage compartment, and blow the cooled air from within the storage compartment among the pans using one or more fans. (see prior art FIGS. 1 and 2). Such storage compartment convection cooled units are relatively simple and inexpensive, but are inherently inefficient from an energy standpoint because the cooling element (also known as the evaporator or blower coil) is located relatively far from the pans, and there is an inefficient flow path for the cooled air between cooling element and pans. The inefficiency is not only costly from an operations standpoint, but is also costly from a maintenance standpoint. Thus, for example, storage cabinet based blower coils often become frozen, which in turn leads to relatively frequent service calls, replacement of the coils, and possible Freon leaks. All of these problems are exacerbated by loss of cold air around the sides of bent and/or missing pans.
In another common method of cooling exposed foods contained in refrigerated food service and display units, the food pans are set into a pan cooler which is segregated from the storage compartment below (see FIG. 3). Here, cooling coils typically wrap around the exterior surface of the inner walls of the pan cooler, and heat is radiated from the pans, through the inner walls of the pan cooler, and then carried away by the cooling coils. While practical in some circumstances, the system is still inadequate because there is not enough cooling surface surrounding the pans to transfer heat between the walls of the food pans and the inner walls of the pan receiving box. The limited heat transfer problem has been addressed by adding ice to the bottom of the pan receiving box (see FIG. 4), but here again the ice is generally not cold enough to adequately cool the food in the food pans.
In still another method, described in our U.S. Pat. No. 5,355,687 (the '687 patent), cooling plates are positioned between adjacent pans. Although the apparatus taught by the '687 patent is quite efficient and cost effective, it may be viewed as being insufficiently adaptable to a sufficiently broad range of pan configurations. A refrigeration unit according to the '687 patent, for example, may have difficulty cooling particularly deep or wide pans, and may not satisfactorily handle unusual arrangements of pans.
Thus, there remains a need to provide refrigerated food service and display units which are efficient, cost effective, and readily adaptable to site specific circumstances.